This is only ideally true. From the perspective of the user of a large closed LLM, this isn't quite right because of non-associativity, experiments, unversioned changes, etc.
It's best to assume that the relationship between input and output of an LLM is not deterministic, similar to something like using a Google search API.
ijk
And even on open LLMs, GPU instability can cause non-determinism. For performance reasons, determinism is seldom guaranteed in LLMs in general.
rar00
yep, even with greedy sampling and fixed system state, numerical instability is sufficient to make output sequences diverge when processing the same exact input
It's best to assume that the relationship between input and output of an LLM is not deterministic, similar to something like using a Google search API.